The present invention relates to multi-leaf collimators. In particular, an arrangement of motors for moving leafs within a multi-leaf collimator is provided.
The leaves of a multi-leaf collimator are moveable to define an aperture through which radiation passes. Any number of leaves and corresponding motors may be provided, such as 60, 80 or 160. Electronic motors drive the movement or positioning of the leaves.
Where a screw drive motor is used for positioning each leaf, the motor is connected at the end of the leaf opposite the end forming the aperture. By shortening or lengthening the shaft of the motor, the leaf is moved along a same or substantially same axis as the motor shaft.
As an alternative to a screw drive, a gear may be provided on the motors to interact with teeth on each leaf. By rotating the gear, the leaf is moved. The motors are positioned in a plane parallel with the plane defined by the movement of the leaves or the aperture. Where the beam of radiation is directed straight down, the motors are positioned horizontally for moving the leaves in a horizontal direction. Since the leaves of each bank of the multi collimator are positioned in parallel or adjacent to each other, the motors are distributed in a same horizontal plane in staggered positions to provide sufficient space for the motors. As a result of the distribution of motors, each of the leaves is sufficiently long to form the aperture and allow the leaf to be driven by for a motor. Alternatively or additionally, different lengths of motor shafts are provided to allow for a tighter spacing of motors. Using different versions or motor shafts may increase the costs and decrease serviceability.